A Simple, Yet Powerful Tool in Robot Trajectory Planning: 5 th Order Polynomials

Authors: Halit Murat GÜLTEKİN, Sedat BAYSEÇ

Abstract: This article is based on a trajectory planning software and briefly describes how 5 th order polynomials are used to form a continuous smooth curve between the precision points in joint coordinate-versus-time space. The robot task is defined by a series of manipulator positions between which the manipulator is required to move smoothly. Universally adopted way of teaching the robot these precision positions is bringing the manipulator to position by manual guidance via a teach pendant and commanding the control computer to read and store the corresponding joint commands. The task can simply be played back by outputting these commands successively in step format. A better way is to smooth a curve between the precision points in joint command and time space. 5 th order polynomials between each successive precision point pairs provide zeroth, first and second order continuities at the intersection of curve segments. Modification of curve slope and radius of curvature at precision points add flexibility to shape up the curve. Developed software is implemented on a Macintosh Centris 650 computer and used to control a heavy duty industrial manipulator. Example trajectories are presented.

Keywords: Industrial Robot, Trajectory Planning, Polynomials.